Pan-Immune-Inflammatory Value Predicts the 3 Months Outcome in Acute Ischemic Stroke Patients after Intravenous Thrombolysis

Background and Purpose Immune and inflammatory response plays a central role in the clinical outcomes of stroke. This study is aimed to explore the clinical significance of the new inflammation index named pan-immune-inflammation value (PIV) in patients with acute ischemic stroke (AIS) after intravenous thrombolysis therapy (IVT). Methods Data were collected from 717 patients who received IVT at the First Affiliated Hospital of Soochow University. Baseline data were collected before intravenous thrombolysis. Multivariate logistic regression analysis was used to assess the association between PIV and 3 months clinical outcome after intravenous thrombolysis. We also used receiver operating characteristic (ROC) curves analysis to assess the discriminative ability of PIV, platelet to lymphocyte ratio (PLR), neutrophil to lymphocyte ratio (NLR), and systemic immune-inflammation index (SII) in predicting 3 months poor outcome. Results Of 717 patients, 182 (25.4%) patients had poor outcomes at 3 months. Patients with 3 months of poor outcome had significantly higher PIV levels compared to those with favorable outcomes [316.32 (187.42-585.67) vs. 223.80 (131.76-394.97), p < 0.001)]. After adjusting for potential confounders, the risk of 3 months of poor outcome was significantly higher among patients whose PIV fell in the third quartile (244.21-434.49) and the fourth quartile (> 434.49) than those in the first quartile (< 139.93) (OR = 1.905, 95% CI: 1.040-3.489; OR = 2.229, 95%CI: 1.229-4.044). The area under the ROC curve of PIV to predict 3 months of poor outcome was 0.607 (95%CI: 0.560-0.654; p < 0.001). The optimal cut-off values of PIV were 283.84 (59% sensitivity and 62% specificity). Conclusion The higher levels of PIV were independently associated with 3 months of poor outcomes in AIS patients receiving IVT. PIV like other inflammatory factors (PLR, NLR, and SII), can also predict adverse outcomes after IVT in AIS patients.


INTRODUCTION
According to the latest Global Burden of Disease Study report, stroke is still the second leading cause of death worldwide, accounting for 11.6% of the total number of deaths, of which ischemic stroke accounts for 62.4% of the total number of strokes [1].Although intravenous thrombolysis therapy (IVT) can reduce neurological deficits in patients with acute ischemic stroke, stroke is still the third leading cause of disability worldwide [2].The identification of biomarkers that can predict the poor outcome of ischemic stroke can help to give these high-risk patients targeted care *Address correspondence to these authors at the Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou, China; Department of Neurology, Dushu Lake Hospital Affiliated to Soochow University, Suzhou, China; Department of Emergency, The First Affiliated Hospital of Soochow University, Suzhou, China; Tels: 13606213892 and 13771800776; E-mails: fangqi_008@126.com;121752769@qq.com# These authors contributed equally to this work.

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in advance and provide more comprehensive medical measures to improve their prognosis.
Recent studies are increasingly exploring the effects of immune-inflammatory mechanisms on clinical outcomes after stroke [3].Inflammatory indicators such as systemic immune-inflammation index (SII), platelet-lymphocyte ratio (PLR), and neutrophil-to-lymphocyte ratio (NLR) have recently been reported to be able to predict clinical outcomes in patients with AIS received IVT [4,5].A novel inflammatory biomarker called pan-immune-inflammation value (PIV) integrates neutrophil, monocyte, platelet, and lymphocyte counts to reflect a more comprehensive status of the systemic immune inflammatory response [6].Compared with SII and PLR, recent studies have found that PIV is a better predictor of mortality in ST-elevation myocardial infarction patients [7].
To our knowledge, the clinical significance of PIV in AIS patients after thrombolysis therapy has not been report-ed.Therefore, this study is designed to explore the relationship between PIV and 3-month clinical outcomes of the patients who received IVT after ischemic stroke.

Patients
We retrospectively collected the details of 812 patients with acute ischemic stroke treated by IVT from January 2017 to August 2022 in the emergency green channel of the First Affiliated Hospital of Soochow University.All patients received intravenous thrombolysis therapy within 4.5 hours of onset.Furthermore, we excluded 46 of the 812 patients who suffered from severe inflammation or infectious diseases, 17 with incomplete baseline data of admission, and 32 who failed to follow up after 3 months.These exclusions resulted in 717 patients finally being included in this study.The flow diagram of the study is given in Fig. (1).Ethical approval for this study was obtained from the ethics committees of our hospital.

Intravenous rt-PA Thrombolysis Therapy
The standard dosage was 0.9 mg per kilogram of body weight (10% as a bolus for 1 min and remaining 90% as an infusion for 1 hour; maximum dose, 90 mg).The low dosage was 0.6 mg per kilogram of body weight (15% as a bolus for 1 min and remaining 85% as an infusion for 1 hour; maximum dose, 60 mg).All patients received only one dose.

Data Collection
The basic information includes age, sex, smoking and drinking history, and antithrombotic medication history (anti-platelet agents or any type of oral anticoagulants).Baseline data at admission include blood pressure, blood glucose, National Institute of Health stroke scale (NIHSS) score, onset to treatment (OTT) time, laboratory data, and Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification.NIHSS score was used by professional neurologists to assess the severity of stroke for all patients at admission.Cigarette smoking was defined as smoking at least one cigarette a day for more than six months [8].Alcohol consumption was defined as consuming at least 1 alcoholic drink every day during the last year [9].Hypertension was defined as the history of taking any type oral anti-hypertensive drugs or previous diagnosis of hypertension or blood pressure higher than 140/90mmHg during hospitalization [10].Diabetes mellitus was defined as previously diagnosed with taking oral hypoglycemic drugs or diabetes diagnosed during hospitalization [10].Atrial fibrillation was defined as previously diagnosed or a clinical diagnosis of atrial fibrillation during hospitalization.Anti-thrombotic was defined as the regular administration of anti-platelet agents or any type of oral anticoagulants before admission [11].Dyslipidemia was defined as any kind of dyslipidemia previously diagnosed or at least having one of the following findings including increased total cholesterol [≥ 240 mg/dL (6.20 mmol/L)], LDL-C [> 160 mg/dL (4.13 mmol/L)], or triglyceride levels [> 200 mg/dL (2.25 mmol/L)] or decreased HDL-C [< 40 mg/dL (1.03 mmol/L)] during hospitalization [12].Previous stroke was defined as having a history of transient ischemic stroke, ischemic stroke, intracerebral hemorrhage, or subarachnoid hemorrhage [10].Follow-up data after three months were obtained by trained nurses through telephone consultation.We used the modified Rankin Scale (mRS) to assess the recovery of patients' neurological function at 3 months which scores ≥ 3 were poor outcomes and scores ≤ 2 were favorable outcomes.

Statistical Analysis
We applied SPSS version 21.0 (SPSS, Inc., Chicago, IL, USA) to analyze the collected data.Variables of normal distribution were expressed as mean ± standard deviation with the sample t-test.Variables of non-normal distribution were expressed as median (interquartile range) with the Mann-Whitney U test.Categorical variables were presented as percentages.The Chi-square test or Fisher's exact probabilities test was used for categorical variables.We divided the calculated PIV level into quartiles, and used the first quartile value as a reference for multivariate logical regression analysis to detect whether the PIV level is independently related to prognosis after three months.Variables with p < 0.05 in univariate analysis were included as the main covariates in the binary logistic regression model.We used variance inflation factors (VIF) to examine multicollinearity and significant interactions between independent variables.The independent variables with multicollinearity relations (VIF>5) were eliminated in multivariate logical regression analysis.In this study, the receiver operating curve (ROC) was applied to analyze the accuracy of the prognosis of PIV, PLR, NLR and SII for the 3-month outcome of AIS patients receiving thrombolysis.The differences in discriminative ability were tested using the DeLong method and use R version 4.0.3software to draw the corresponding figure.A p < 0.05 was considered statistically significant.

Patient Characteristics Between Favorable Outcome Group and Poor Outcome Group
The baseline characteristics between favorable outcome group and poor outcome group were provided in Table 1

Receiver Operating Characteristic Curve Analysis for 3-Month Outcome
Receiver Operating Characteristic (ROC) curve analyses were performed to compare the predictive performances among PIV and other popular inflammatory indexes, such as SII, PLR and NLR in Table 3 and Fig. (3).According to the ROC curve analysis, the optimal cut-off value of PIV that best discriminated poor outcome was 283.84 (59% sensitivity and 62% specificity).There was no significant difference in efficiency between PIV and other popular inflammatory indexes for predicting poor outcomes (PIV vs. SII: 0.607 vs 0.598, p = 0.478; PIV vs. PLR: 0.607 vs. 0.564, p = 0.059; PIV vs. NLR: 0.607 vs 0.617, p = 0.541).

DISCUSSION
In this study, we found that the higher the PIV level, the higher the risk of 3 months poor outcome in AIS patients after IVT.Through multivariate regression analyses, PIV level was significantly correlated with 3 months poor outcome of patients receiving thrombolysis.The ROC curve showed that PIV had a similar predictive ability for the 3 months poor     outcome after thrombolysis compared to SII, PLR and NLR.
There was no significant difference in their predictive ability.To our best knowledge, this is the first study to investigate the association between PIV and the 3 months clinical outcomes of AIS patients receiving IVT.
After cerebral ischemia injury, the damage-associated molecular patterns (DAMPs) released by necrotic cells activate resident immune cells in the central nervous system, such as microglia and astrocytes, which subsequently attract peripheral immune cells to activate adaptive immune responses [13].The activated immune system along with the deactivated neuroendocrine and autonomic nervous systems, link the center with the periphery, leading to the systemic immune inflammatory response [14].There is increasing evidence to suggest that the global immune inflammatory response can affect the clinical outcomes of stroke [15,16].Liu et al. reported that patients with poor prognosis after intravenous thrombolysis had higher NLR values [17].In 2022, studies found that SII was closely related to the short (90-day) and long (1-year) term prognosis of patients with acute ischemic stroke, and patients with higher SIIs were more likely to have poor outcomes [18].In another study, Xu et al. found that patients with unfavorable outcomes had significantly higher PLR than those with favorable outcomes, and the PLR values of the patients who died at 3 months were higher than those of the surviving patients [19].What's more, Gong et al. discovered that PLR and NLR was associ-ated with post-thrombolysis early neurological deterioration [5].Our study revealed that 3 months poor outcome group had significantly higher PLR, NLR and SII values compared to the group with favorable outcome.In addition, we found that PIV levels were elevated in the poor outcome group and determined that the high level of PIV was an independent risk factor for poor outcome at 3 months after IVT in AIS patients.Fuca et al. identified PIV as a new Immuneinflammatory biomarker in patients with metastatic colorectal cancer (mCRC), and PIV had a stronger predictor of survival outcomes in first-line therapy mCRC patients than SII and PLR [6].A systematic review evaluated the association between survival and PIV in cancer (colorectal cancer, melanoma, breast cancer, and non-small cell lung cancer), the results showed that patients with higher PIV levels had a significantly higher risk of death than patients with lower PIV levels, and the risk of disease progression or death was increased in patients with higher PIV levels [20].In cardiovascular disease, Murat et al. found that PIV was better than PLR and SII in predicting one-year and one-month all-cause mortality in STEMI patients [7].The Immune and inflammatory response is a common process in the clinical manifestations of cardiac and cerebral acute ischemia following atherothrombosis [21].Therefore, PIV as a more systematic inflammation index, should also be considered when assessing the effect of inflammation on the clinical outcomes of AIS patients after IVT.
Previous studies showed that high SII, NLR and PLR are independent predictors of the independent risk factors for poor prognosis at 3 months of AIS patients [4,22,23].In this study, we found that PIV was not inferior to SII, NLR, or PLR in predicting the prognosis of ischemic stroke, but not superior to any of them.This may be because the PIV data in this study came from laboratory data at the time of admission.It has been confirmed that the predictive power of inflammation indicators 24 hours after thrombolytic therapy was stronger than that at admission [24].Compared to SII, NLR and PLR, PIV includes not only lymphocyte and platelet, but also monocyte and neutrophil, suggesting that PIV is a more systemic indicator of inflammation.However, the immune inflammatory response in ischemic stroke is a dynamic process [25].This may have contributed to the fact that PIV at admission in this study did not show a significant advantage compared to other traditional biomarkers.
This study still has several potential limitations.First, this is a retrospective study from a single center, and the results are limited by the sample size and study population.Secondly, some risk factors that may be associated with poor outcome after thrombolysis in ischemic stroke patients, such as hyperhomocysteinemia [11] and plasma high mobility group box protein 1 [26], we were not able to capture and further analyze such potential factors.Third, PIV from AIS patients after thrombolysis was not further analyzed in this study, and whether changes in PIV before and after thrombolysis are more valuable needs further investigation.Moreover, previous studies have shown that higher levels of inflammation are associated with an increased incidence of stroke-associated pneumonia and post-stroke depression [27][28][29], and the long-term prognosis of PIV after stroke should be further studied.Despite these limitations mentioned above, this study is the first to report the relationship between PIV levels and clinical outcome in patients with acute ischemic stroke after intravenous thrombolysis.

CONCLUSION
The higher levels of PIV were independently associated with poor outcome in AIS patients receiving thrombolysis.PIV had a similar predictive ability compared with popular biomarkers like PLR, NLR and SII for 3-month poor outcome.

Fig. ( 2 ).
Fig. (2).Distribution of PIV levels in the favorable outcome group and poor outcome group.

Fig. ( 3 ).
Fig. (3).Receiver operating characteristic curves of PIV, PLR, NLR and SII on the prognosis of AIS patients treated with IVT.(A higher resolution / colour version of this figure is available in the electronic copy of the article).
of Org 10172 in Acute Stroke Treatment VIF = Variance Inflation Factors

Table 2 . Multivariate-adjusted odds ratios for clinical outcome stratified by PIV levels.
Model 1 is a univariate analysis.Model 2 is adjusted for age and sex.Model 3 is adjusted for age, sex, NIHSS score, TBIL, glucose, diabetes mellitus, atrial fibrillation, history of stroke, TG, HDL, and TOAST classification.

Table 3 . Diagnostic values of the PIV, SII, PLR, NLR for poor outcome in AIS patients after IVT.
Note: p* for comparison of AUC between groups; Abbreviations: AUC, area under the curve; CI, confidence interval; PIV, pan-immune-inflammation value; SII, systemic immune-inflammation index; PLR, platelet to lymphocyte ratio; NLR, neutrophil to lymphocyte ratio.